export default {
	// 为当前模块开启命名空间
	namespaced: true,

	// 模块的state数据
	state: () => ({
		// 每个商品的信息对象，都包含如下 6 个属性：
		// { goods_id, goods_name, goods_price, goods_count, goods_small_logo, goods_state }
		cart: JSON.parse(uni.getStorageSync("cart") || '[]' )
	}),
	// 模块的 mutations 方法
	mutations: {
		addToCart(state, goods) {
			// 根据商品提交的id，查询购物车中时候存在这件商品
			const findResult = state.cart.find(x => x.goods_id === goods.goods_id)

			if (!findResult) {
				state.cart.push(goods)
			} else {
				findResult.goods_count++;
			}
			this.commit("m_cart/saveToStorage");
		},
		saveToStorage(state) {
			uni.setStorageSync('cart', JSON.stringify(state.cart));
		},
		updateGoodsState(state, goods){
			const findResult = state.cart.find(x => x.goods_id === goods.goods_id);
			if(findResult){
				findResult.goods_state = goods.goods_state;
				// 持久化存储到本地
				this.commit('m_cart/saveToStorage');
			}
		},
		updateGoodsCount(state, goods){
			const findResult = state.cart.find(x => x.goods_id === goods.goods_id);
			if(findResult){
				findResult.goods_count = goods.goods_count;
				// 持久化存储到本地
				this.commit('m_cart/saveToStorage');
			}
		},
		removeGoodsById(state, goods_id){
			// 调用数组的filter方法过滤
			state.cart = state.cart.filter(x => x.goods_id !== goods_id)
			// 持久化存储到本地
			this.commit('m_cart/saveToStorage')
		},
		updateAllGoodsState(state, newState) {
		  // 循环更新购物车中每件商品的勾选状态
		  state.cart.forEach(x => x.goods_state = newState);
		  // 持久化存储到本地
		  this.commit('m_cart/saveToStorage');
		}
	},

	// 模块的 getters 方法
	getters: {
		total(state) {
			let c = 0;
			state.cart.forEach(goods => c += goods.goods_count)
			return c
		},
		// 勾选的商品的总数量
		checkedCount(state) {
		  return state.cart.filter(x => x.goods_state).reduce((total, item) => total += item.goods_count, 0)
		},
		checkedGoodsAmount(state) {
		  // 先使用 filter 方法，从购物车中过滤器已勾选的商品
		  // 再使用 reduce 方法，将已勾选的商品数量 * 单价之后，进行累加
		  // reduce() 的返回值就是已勾选的商品的总价
		  // 最后调用 toFixed(2) 方法，保留两位小数
		  return state.cart.filter(x => x.goods_state)
		                   .reduce((total, item) => total += item.goods_count * item.goods_price, 0)
		                   .toFixed(2)
		}
	}

}
